Olympique Marseille is ranked second on the Ligue One table, they're competing with Monaco who's sitting at the first position. Checking out I didn't see PSG in the crucial positions, moreover it's very early to start concluding on the club's that would be in the race to fight for the domestic league title.
It's true that it's too soon to draw conclusions about which teams will be strong candidates to win the Ligue 1 title, there are still 31 games remaining ahead of us. We are also used to seeing underdog teams ranked at the top at the start of the season, soon we'll see how the big teams will get rid of them. Ligue 1 has only played 3 matches so far, and the interesting thing I see is that of the three matches that have been completed, not a single team has finished with a perfect result (9 points).
It is normal to see PSG in this situation now. Because they have been making big changes in the squad. Mbappe was also nearly leaving and he has been integrated into the squad again after some issues between him and the team. They tried a trio without Mbappe first. Despite the dominance it didn't work out as they couldn't score a goal. Whenever Mbappe was in the game he made a direct impact on the game with his goals later on. As I said before he is the mainstay for now.
As long as they have him in the starting eleven their win percentage should be increasing by a high sum. But I don't have big expectations from them anyway as I need to see the adaptation process of the new players first.
But the truth is, Monaco and Marseille are not mediocre teams so yes, if Monaco and Marseille can maintain this kind of good performance. Then at least, PSG might find it difficult to be at the top of the table. Indeed, it is still early and of course any result is still very possible, but if I consider PSG relies heavily on Mbappe to score goals. So if at any time later Mbappe cannot be played, then of course PSG will find it difficult to consistently win in every match. If that happens, then maybe this season PSG no longer has a strong dominance to be able to win the Ligue 1 title.